IMO, part of the reason for the lack of "damage" is that he didn't know it was in there.
Seen some interesting research into strokes that show that if a patient arrives unconscious, then placing them in a full body cast limited the paralysis, as they didn't know that they couldn't move "x" part of their body, until some point in time after they had started recovering...
Nailgun instances ?
Former workmate nailed himself to a fascia board through the web of his left hand, while (obviously) up a ladder...decided to rip it off.
Another current workmate was nailing a benchtop on his daughter's renovation, and as he changed timber cross-sections, sent a nail up through the benchtop into his gesticulative finger, pinning him in place...couldn't reach phone to call wife, wouldn't be missed for hours, so freed himself with a claw hammer.